1. Field of the Invention
The present invention relates generally to hazardous location communications and, more specifically, to telephones in a voice over Internet Protocol (VoIP) system that are designed to incorporate, for example, UL Class I Division I protection methods, as well as provide improved multicast capabilities such as hazardous area WiFi, loudspeaker-zoned paging, and prioritized paging groups.
2. Description of Related Art
To regulate the design of equipment used in potentially explosive atmospheres, special certification schemes and governing organizations have been established in various regions globally. In other words, equipment in hazardous locations or areas can be designed to comply with safety standards and thereby gain approval from safety standards organizations such as Underwriters Laboratories (UL). Safety standards organizations can have different definitions or classifications for hazardous locations. For example, a UL Hazardous Location is an explosive atmosphere due to the presence of flammable gases, vapors, or liquids (Class I), combustible dusts (Class II) or ignitable fibers or flyings (Class III). An area may also be considered “hazardous” for other reasons, such as the use of electrical equipment in the vicinity of water, the risk of personal injury from moving or falling parts, or even the presence of biological hazards. While hazards are associated with all of these conditions, areas are only considered hazardous (classified) locations under conditions defined by the NEC, CEC, IEC 60079-10, or CENELEC EN 60079-10 or similar certification organization(s), as applicable. This approach to classifying hazardous locations is used by the United States (National Electrical Code), Canada (Canadian Electrical Code), Europe (CENELEC EN60079-10) and throughout the world (IEC 60079-10). Other certification organizations and/or schemes for equipment used in classified hazardous locations can include, but are not limited to, ATEX directives 94/9/EC and 1999/92/EC in the European Union, North America laboratories such as Intertek (ETL), Factory Mutual (FM), Canadian Standards Association (CSA) and the IECEx International Certification Scheme.
Examples of hazardous locations can be various industrial sites such as land and offshore oil rigs, chemical plants, refineries, mills, and loading facilities, which can be subjected to harsh environments, as well as create potentially unsafe environments due to the presence of gases or other combustible materials. It can therefore also be desirous to obtain ABS-type approval to assure that marine vessels and offshore structures comply with rules promulgated by the American Bureau of Shipping (ABS) for design, construction and periodic survey.
A need exists for an IP telephone that can provide loud ringing (e.g., for peer to peer communications) and loud WiFi IP-based paging (e.g., to provide alerts for emergency responses) with multicast capabilities in a hazardous location such as an industrial site that is often characterized by significant ambient noise level due from use of heavy equipment. A need also exists for such an IP telephone to carry UL certification for Class 1 Division 1, Groups, B, C and D, and Class II Division 1 Groups E, F and G and Class III, or similar safety standard approval, at a minimum, and IEC Zone 1, at a minimum.